At any one time, a person is likely to be close to at least three to four wireless devices, such as smart phones and tablets. Those devices would include not just his or her own, but also ones belonging to other people nearby. At airports or shopping centers, the number of people, and thus the number of devices, can be substantially higher. ADSC Research Scientist Binbin Chen is looking into how to capitalize on these close quarters to help phones save energy.

“Phone batteries are used up on lots of useless things,” Chen said. “Even when the screen is off, it’s doing things in the background, and up to 60 percent of the phone’s energy can be wasted in this state.”

Low-frequency, low-data-rate background traffic, such as push notifications or incoming emails, can drain phone batteries quickly, but by using low-power Bluetooth radio and sharing cellular bandwidth, Chen and his team have saved up to 90 percent of background traffic energy consumption in urban settings. The team developed a middleware on Android to automatically enable the use of Bluetooth radio for sharing cellular bandwidth, but only during times when it would be useful for collaboration.

While other researchers have been looking into solutions to this problem, Chen’s method takes a different approach by looking into how phones can collaborate with each other.

“Normally phones won’t be alone and will be nearby other phones,” he said. “All devices can form a local community that collaborates, so we’re trying to develop a way for the phones to recognize each other and piggyback on other people’s usage in an energy efficient way.”

Chen said that if only two to three people piggyback off of each other, a phone can save about 10 percent of energy, but if there are 10 devices nearby, a phone can save more than 50 percent of its energy. To help ensure equality between users, the team developed an algorithm that schedules users to take turns to become contributors to the collaborating system based on each user’s individual use patterns and the team’s proposed fairness notion.

Chen and his fellow researchers believe the combination of the characteristics of background traffic and Bluetooth is the key to helping save energy, because while Bluetooth consumes little power, it is slow. Luckily, the background traffic is very small in size and can tolerate wait times, which makes Bluetooth ideal for this type of work.

Chen and his team have been determining if this method is feasible through real prototypes and conducting simulations on a larger scale. They have also designed a solution that ensures the method is fair to all users while maintaining as much efficiency as possible.

“Even 10 years ago, we were just beginning to be affected by smart phones,” he said. “Think about how many things have changed since then and what will happen in the next 10 years. We could be surrounded by hundreds of devices that talk and collaborate with each other.”

Chen believes this technology could be incredibly useful in the future, as energy is always a top constraint in developing new Internet of Things applications.

One concern that hasn’t been addressed yet is security challenges that will arise as a result of this type of collaboration. Chen, who works with ADSC’s cybersecurity team, began the project on the side a few years ago, but foresees future research on this topic fitting in with ADSC’s current work.

“We haven’t touched on the cybersecurity aspect of the project yet, but with phones collaborating like this, security is very important,” he said. “Not only is the phone talking to the server, but it now sends traffic through its neighbor, so there are a lot of security and privacy issues that still need to be addressed. It’s a work that can lead to a lot of interesting mobile computing security, Internet of Things security and mobile application security research.”